Spark plug



May 8, 1923.

W. MCELROY SPARK PLUG 2 sheets-'sheet 1 Filed Feb. 10 .'1921 .47 ORNE Y May 8', 1923.

SPARK PLUG l Filed Feb. 10 1921 2 Sheets-Sheet 2,

AT RAEY Patented May s, 1923.

.'UN'ITED vSTATES PATENT Ol'F-ICE.

y T\KTII.-LI.Al.I MCELROY, 0F BROOKLYN, NEW YORK.

SPARK PLUG.

Application led February 10, 1921.

To all whom it may concern:

yBe it known that I, VVILLrAM MOF'LROY, a citizeniof the 'United States, residing at New. York city, borough of Brooklyn, in

, and operable that, when desired, compressed or burninghgases from the cylinder with whichthefplug is associated maybe eX hausted through the `plug for the purpose .of freeing-the same from carbon deposit, dirt and oil.

The object vof the invention is to provide a plug of this character which will be simple in construction and devoid of valves of the character usually employed for this purpose. Such Valves have been found, in practice, to warp, become pitted or otherwise fail toy hold compression during the normal operation of the engineand to this end, the present construction is so organized as to entirely overcome these difficulties.

The plug of the present invention is preferably so constructed that it may be oper- .able from within the vehicle and from the drivers seat thereof. 'Howeveig the inventionis-not restricted in this respect since the operative connections leading to a point within the car may be dispensed with and the plugsfoperated locally by a wrench after raising the hood of the car.

An important feature-of the present invention resides in the marked simplicity of construction of the plug of the present invention, the lminimum number of parts necessary for the carrying out thereof and the ability of the plug to withstand long and steady use wit-hout becoming leaky and failing to properly hold compression inthe cylinder.

Features of the invention, other than those specified, will be apparent from the hereinafter detailed description and claim, when read in conjunction with the accompanying drawings.

The accompanying drawings illustrate different practical embodiments of the present invention, but the constructions therein shown are to be understood as illustrative,

only, and not as defining the limits of the Serial No.` 443,787.

the present inventiom showing half in section and half inelevation.

`Figure 2 is a plan view of the plug shown in Figure 1.

Figure 3 is a view similar to Figure 1, but illustrating a modified formo plug.

Figure 4 is a plan view of the partsof the plug shown in Figure 3.

Figure 5 is a view corresponding to Figure 3, but showing the partsA indifferent positions.

Figure 6 is a plan view showing the parts in the positions shown inFigure 5.

Figure 7 is a detail of a locking ring employed; and, y y

Figure 8 is a diagrammatic showingl of certain operative connections Awhereby the seieral plugs of a motor vehicle engine are operable from the drivers seat.

ln the drawings, Figures 1 and 2 show a simple form of plug so constructed that it is adapted` to be operated manuallyby a wrench after the hood of the machine has been raised, while in Figures 4 to 8, inclusive, ineans is shownV associated with'the plug of the same character as 'shown' in Figures 1 and 2 whereby theplug is made operable from a distance soI thatthe raising of the hood is rendered unnecessary. In this latter construction, the vdriver may, while seated in the car, blow out anyone or more plugs as desired.

Referring first to the construction shown in Figures 1 and 2, 10 designatesthe shell of the plug, the lower end of the shell is exteriorly threaded at 11 to screw into a tapped hole in the cylinder head in the usual manner and carries at its lower end one electrode 12. Substantially the upper half of the shell 10 is hexagonal in shape and is interiorly threaded at 13 to receive' the threaded shank of a tubular plug 14, the head of which tubular plu is also hexagonal.

The second electrode 15 extends directly through the spark plug and is housed within a suitable insulating core member 16 which may be conveniently and economically formed of porcelain, although it is not restricted to this particular material sinceit may be of mica or any other suitable insulator. For the purpose `of terse *description, however, the member 16 will hereinafter be called the porcelain.V The upper end of the electrode 15A is threaded to lreceive a binding screw 17 of the usual kind by means'of which one lead of the ignition cirlof the shank of the screw plu cuit may be electrically connected to the electrode 15. The porcelain 16 is provided intermediate its ends with an enlarged portion 18, which is adapted to be clamped by means of the screw plug 14 between the lower end of said plug and a shoulder 19 formed in the shell 10. A gasket of asbestos, copper or any other suitable material 20 seats on the shoulder 19 and serves to insure a tight joint between the enlarged portion 18 and the shoulder 19 when the screw plug 14 is screwed down tight. A gasket 21 is preferably interposed between the lower edge and the enlarged portion 18 of the porce ain.

irectly above the shou der 19, the wall of the shell 10 is apertured to provide holes 22. Any number of such holes may beformed in the shell, but I have shown one passing through each ,hexagonal face thereof. In practice, however, one hole would be enough. In the normal operation of the spark plug, the threaded plug 14 is screwed down tight, causing the enlarged portion 18 of the porcelain tol form a tight seat with the gasket 20. `The plug functions in the usual way until such time, as, in the opinion of the car operator, it should be cleaned. This time may manifest itself by improper functioning of the plug occasioning missing in the engine cylinder with which it is associated. If the fault is with the plug, the robabilities are that the interior of the plug as accumulated a deposit of soot, carbon or oil, or a combination of all three. In order that the engine may properly function, such extraneous material must be removed and this may be accomplished by lifting theV porcelain 16 to be lifted under the force of compression within the cylinder or the firing pressure therein so that the enlarged portion 18 of the porcelain is unseated from the gasket 20, thereby permitting gaseous pressure to blow off through the plug and find exit through the holes 22. This blowing ofl'l of gaseous pressure directly through the interior of the plug, results in a scouring action within the plug, which, in practice, will efficiently free the entire interior of the plug of deposits of carbon, soot, oil and such other extraneous material as may have become lodged therein.

The blowing off of the gases under pressure is found to effect a thorough cleansing of the interior of the plug, both as regards the inner wall of the shell 10 and the exposed surface of the lower portion of the porcelain 16, so that after two or three strokes of the piston, the threaded plug 14 may again be screwed down tight to force the enlarged portion 18 of the porcelain again to its seat and permit the engine to function in the usual manner.

The gases which effect the blow out of the plug are under high pressure so that the deposits within the plug are forcibly ejected through the holes 22 and to preclude such deposits from being dispersed broadcast on to the clothing of the operator, or effecting injury to his eyes, I preferably rovide an apron 24 of cylindrical form an provided at its top with an inturned flange 25 adaled to be clam ed between the head of t e screw plug an the upper edge of the shell after the manner shown in Figure 1. The apron is of such diameter as to permit of free exit of the blow off gases, but is of suflcient lengt-h to extend below the holes 22, so that the force of the blow off is directed downwardly and is not spent broadcast as would otherwise be the case.

In the construction of Figures 4 to 8 in` elusive, the same generic principles of construction as described with reference to Figures 1 and 2 are present, but are enlarged upon and added to in order to enable the plug to be controlled from a distance. In this modified construction, a shell 10* has a screw plug 14n which threads into the upper portion thereof and the holes 22i which correspond to the holes 22 are covered by an apron 24a, the inturned flange of which is"A seated on a shoulder 26 formed by stepping down the upper portion of the shell adjacent the top thereof. The head 14b of the screw plug 14a instead of being hexagonal in shape as shown in Figures 1 and 2 is made circular and is provide at spaced distances around its periphery with cut out portions 27. Mounted for rotation on the shank of the screw pluv 14 and between the head 14" thereof and the upper edge of the shell 10" is a plate 28 which is provided with a laterally extending arm 29 and between the head 14b and plate 28 is interposed a locking member 30, shown in detail in Figure 7.

The locking member 30 is stamped up' from resilient sheet metal and is provided with a laterally extending arm 31 from which is struck up a projecting nose 32.

rfhe annular portion of the member 30 enl circles the shank of the screw lug 14, and the arm 31 is bent downward y through a cut out portion 33 in the plate 28 so as to bring the nose 32 into engagement with the stepped down ortion at the upper end of the shell 10a. his stepped down portion i3 preferably milled vertically as at 34, so that the nose 32 will engage with the milled portion and by virtue of the fact that the arm 31 extends through the cut out portion 33 of the plate 28, will serve to lock the plate 28 against inadvertent rotation relative to theshell. It willv` appear, however, that if sufficient force is applied to the arm 29, the nose 32 may bey caused to travel over the milled surface of the shell. Engagement between the ends andl` milled surface will, however, normally hold the parts against rotation.

Supported on the arm 29 is a locking member 35 which is provided with a longitudinal slot 36 through which extends a threaded stem of a clamping screw 37. The threaded stem is tapped into the arm 29 so that when the screw is screwed down tight, the head thereof will clamp the locking member 35 against sliding movement on the arm 29.

The forward end of the locking member is provided with a tooth 38 oit' such size and shape as to adapt it to enter any one of the cut out portions 27 in the head ot the screw plug 14, and when the parts are thus engaged and the clamping screw 37 tight, the operation of the arm 29 will manifestly effect rotation of the screw plug 14a to shift the position of the parts :trom that shown in Figures 3 and 4 to that Shown in Figures 5 and 6 or vice versa and in accordance with the direction of movement of the arri 29, so that in this manner the plug may be sealed or unsealed for normal operation or to permit of the blowing out or the plug. It will appear, as shown best in Figure 3, that the outer end of the locking member 35 and that portion on which the clamping screw 37 is adapted to seat when the parts are locked together, is stepped down to provide a shoulder 39, so that even though jar or vibration slightly loosen the clamping screw, the locking member cannot retract until the clamping screw has been unscrewed to the dotted line position of Figure 3, wherein the lower face of its head will have been raised above the highest portion of the locking member 35.

When the engine of a motor driven vehicle has associated therewith spark plugs embodying the present invention as outlined in Figures 4 to 7, the operating arms 29 of the respective plugs may be connected by means of push rods 40, which extend through' a dash or instrument board 41 of the vehicle to operating handles 42, so that a person seated in the drivers seat oi' the vehicle may reach down, and by operating the handles 42 eitect perfect control of all of the plugs.

A spark plug embodying the present invention may be readily associated with any engine without in anywise requiring change in the mechanism associated therewith.

It may be here noted that in installing plugs oi' the invention as typified in Figures 4 to 8 inclusive, the spark plugs are screwed into the tapped holes in the engine in the usual way. This having been done, the clamping screws 37 are unscrewed, thereby allowing the locking members 35 t0 be retracted. The push rods 40 are next coupled up whereupon the locking members are again moved forwardly and engaged into the nearest cut away portion 27 oi which several are provided in each plug to permit of this operation. The clamping screws27 are then tightened and the assembly is ready for operation.

I wish it here understood that while I have shown a speciic form of locking member 35 and clamping screw 37 for locking the operating plate to the operating arm, the present invention is not limited to this speciiic construction as any suitable mechanism or means for accomplishing this result may be availed of without departing from this invention, and, if desired, the screw plugs of each spark plug may be provided with an integral laterally extending arm to which the push rods leading to the operating handles 42 may be pivoted.

F rom the foregoing detailed description of the invention, it will be apparent that the plug of the invention is of simple construction and embodies such substantial parts that there will be no liability of its getting out of order. Moreover, there are no parts which are apt to warp or pit in such manner as to result in an inelicient seal which would preclude the engine operating under proper compression. The device is simple and etlicient in operation and the blowing out of the plug is effected in such manner that all parts oi the plug are thoroughly cleaned.

lf it be desired to dismantle the parts of the spark plug for any purpose, this may be readily accomplished by merely removing the screw plugs 14 or 14a, whereupon the porcelain may be removed. During this operation, there is a possibility that the porcelain might drop out of the screw plug and become broken, but this is overcome by seating a spring ring 43 in an annular groove in the porcelain as clearly shown in Figs. 1, 3 and 5. The ring 43 thoroughly safeguards the porcelain against dropping out when the screw plug is removed.

I am aware that changes in construction, such for example as the substitution or' equivalents may be made without departing from the spirit of this invention which is to be understood as broadly novel as is commensurate with the appended claim.

Having thus fully described the invention, what l claim as new and desire to secure by Letters Patent is;

A spark plug embodying a shell, adapted to be screwed into the spark plug hole of an engine, provided intermediate its top and bottom with a shoulder and having its wall apertured above said shoulder, an insulating core extending through the shell and having an enlarged portion seated on the shoulder, a screw plug embracing the core and threaded into the shell to bear against the enlarged porton of the core and normally effect a tight seating of the enlarged portion of the latter upon the shoulder of the shell7 but operable, when retracted, to allow the core to lift to permit carbon deposits in the plug to be blown out through the apertures in the shell, and an apron positioned exteriorly of the shell and overlynv the apertures in the Wall thereof to preclue broadcast distribution of the blown-off de osits.

In testimony whereo I have Signed my name to this. specification.

WILLIAM MCELRO Y. 

